The present invention relates to a double-headed piston compressor for an air conditioner used in vehicles.
As shown in FIG. 7, a typical double-headed piston compressor includes front and rear cylinder blocks 101, 102, which are joined together. A front housing member 103 is attached to one end of the front cylinder block 101. A rear housing member 104 is attached to the other end of the rear cylinder block 102.
A drive shaft 105 is rotatably supported by the cylinder blocks 101, 102, and the front housing member 103. Cylinder bores 106 are formed in the cylinder blocks 101, 102. The cylinder bores 106 formed in the front cylinder block 101 correspond to those in the rear cylinder block 102. Double-headed pistons 107 are accommodated in the cylinder bores 106 and are connected the drive shaft 105 through a swash plate 108. A suction chamber 109 and a discharge chamber 110 are formed in each of the front and rear housing members 103, 104.
Rotation of the drive shaft 105 is converted into reciprocation of the pistons 107 by the swash plate 108. The pistons 107 draw refrigerant gas to the corresponding cylinder bores 106, compress the gas, and discharge the gas to the discharge chambers 110. Then, the compressed refrigerant gas is sent to an external refrigerant circuit.
Each piston 107 intermittently discharges refrigerant gas from the corresponding cylinder bore 106. The intermittent discharge of compressed gas generates pressure pulsation, which causes vibration and noise in the external refrigerant circuit. Therefore, in the compressor of FIG. 7, a muffler chamber 118 is formed on the outer circumferential portions of the cylinder blocks 101, 102. Refrigerant gas that is discharged from the front and rear discharge chambers 110 flows to the muffler chamber 118. The muffler chamber 118 attenuates the pressure pulsation of the refrigerant gas before sending the gas to the external refrigerant circuit.
In the past, attenuation of the pressure pulsation was accomplished by increasing the volume of the muffler chamber 118, which increased the size of the compressor. However, there is a need to improve the attenuation of the pressure pulsation without increasing the size of the compressor.
An objective of the present invention is to provide a double head piston compressor that can attenuate pressure pulsation of discharged gas without increasing the size of the compressor.
To achieve the above objective, the present invention provides a compressor including a drive shaft and a drive plate, which is supported by the drive shaft. A piston is coupled to the drive plate. The piston includes two opposed piston heads, and the drive plate converts rotation of the drive shaft into reciprocation of the piston. A pair of compression chambers correspond to the piston heads. A pair of discharge chambers correspond to the compression chambers. Each compression chamber is connected to a corresponding one of the discharge chambers through a respective discharge port. The piston heads compress gas in the corresponding compression chambers and discharge compressed gas from the corresponding compression chambers to the corresponding discharge chambers. Each discharge chamber has an outlet for compressed gas. A limit wall is formed in each discharge chamber. Each limit wall limits the flow of compressed gas in the corresponding discharge chamber so that compressed gas in the corresponding discharge chamber flows circularly about the axis of the drive shaft in one direction from the discharge port toward the outlet.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.